A Russian court has resumed the preliminary hearing into the high-profile case against Ukrainian pilot Nadia Savchenko, charged with providing information that led to the deaths of two Russian journalists.

The hearing in the town of Donetsk in Russia's Rostov region is being held behind closed doors.

Russian officials say Savchenko, who served in a volunteer battalion in eastern Ukraine where Ukrainian forces are fighting Russian-backed separatists, provided the coordinates for a mortar attack that killed the journalists last summer.

Savchenko strongly denies the charges and says she was captured by rebels in Ukraine and smuggled into Russia. She had gone on a hunger strike to protest her detention.

International rights groups and many Western governments have called for Savchenko to be released.

Last month, the Rostov regional court rejected a defense request to move Savchenko's trial to Moscow.